Some injection molding machines use an induction coil to melt material before injecting the material into a mold. However, in horizontally disposed machines where the material is melted in a vessel positioned for horizontal ejection, gravitational forces on the molten metal, in addition to magnetic fluxes from the induction coil tend to cause the melt to move away from the region of highest magnetic flux, e.g., to flow towards and/or out of the melt zone, which can make it difficult to control the uniformity and temperature of the melt.
Current solutions for melting in vessels designed for horizontal ejection include use of a gate that is in contact with the melt and physically blocks the melt from flowing (horizontally) out of the induction coil in the melt zone. Problems arise, however, due to gate configurations, wherein the gate is a point of contact with the melt and impurities may be introduced by the gate. In addition, the gate configuration may reduce the space available for the melt zone because the gate must be actuated up and down in order to allow the melt to flow. Further, the melt may undesirably flow towards and/or out of the horizontal ejection path of the vessel due to challenge of the timing control as when to raise the gate during the injection process of the melt. Also, even if the gate material is insulating, the gate will pull heat from the melt, thus locally reducing the temperature of the melt, negatively affecting the castability of the molten alloy. Furthermore, the gate is potentially a consumable part and needs to be replaced after a certain number of uses which increases the cost per cast on the system.
It is desirable to contain the melt in the melt zone of horizontally designed systems at desired high temperatures when it is heated or melted, but without introducing a gate to physically block the melt.